Allergy

Question 1

What common allergic diseases are seen in children? (8)

Answer 1

• Food allergy
• Eczema
• Asthma
• Allergic rhinitis
• Conjunctivitis
• Urticaria
• Insect sting
• Anaphylaxis

Question 2

What are the two phases of IgE-mediated allergic response?

Answer 2

Early phase (minutes): Histamine, causing urticaria, angioedema, sneezing and bronchospasm

Late phase (4-6 hrs): Nasal congestion in upper airway, cough and bronchospasm in lower airway.

Question 3

What important features should be investigated in an allergic history?

Answer 3

• Mouth breathing – obstructed airway from rhinitis – history of snoring/apnoea
• Allergic salute (rubbing itchy nose)
• Pale and swollen nasal turbinates
• Hyperinflated chest/Harrison sulci from chronic untreated asthma
• Atopic eczema in flexures
• Allergic conjunctivitis
• Check growth (especially if food allergy)

Question 4

What is intolerance?

Answer 4

Non-immunological hypersensitivity reaction to specific foods.

Question 5

Why do children get food allergy?

Answer 5

Failed to develop immune tolerance to relevant food.

Question 6

What are the clinical features of IgE-mediated allergic reaction? (6)

Answer 6

Mild reaction:
• Urticaria
• Facial swelling

Severe reaction:
•	Wheeze
•	Stridor
•	Abdo pain, vomiting diarrhoea
•	Shock, collapse

Question 7

What are the clinical features of non-IgE-mediated allergic reaction? (7)

Answer 7

• Diarrhoea
• Vomiting
• Abdo pain
• Failure to thrive

Less common:
• Colic
• Eczema
• Blood in stool

Question 8

How is allergy diagnosed? (3)

Answer 8

IgE-mediated:
• Skin prick test (screening)
• Measure IgE antibodies in blood (RAST test)

Non-IgE-mediated:
• Clinical history and examination (Endoscopy/intestinal biopsy can be done – eosinophilic infiltrates indicates allergy)

Gold standard = exclusion of food, then double-blind placebo-controlled food challenge – given increasing amounts of food/placebo, starting with tiny amount, until full portion reached.

Question 9

What are the clinical features of eczema?

Answer 9

• Itching (pruritis) – scratching, erythema, weeping and crusted
• Dry skin – prolonged scratching/rubbing leads to lichenification (thick, leathery)

Question 10

What is the management of eczema? (7)

Answer 10

• Avoid irritants and precipitants
• Emollients (moisturising and softening skin)
• Topical corticosteroids
• Immunomodulators
• Occlusive bandages
• Antibiotics if infected
• Dietary elimination

Question 11

What is the classic presentation of allergic rhinitis and conjunctivitis?

Answer 11

Coryza
Conjunctivitis

Can also present as cough-variant rhinitis and chronically blocked nose causing sleep disturbance.